what does this option do ?
Enabling this means that your bitmaps and uvw modifier use real-world settings by default so you don't have to manually turn them on every time you import the bitmap or apply the modifier. Saves you a few clicks I suppose, I would still use box instead of planar mapping but handy regardless.
Also when creating/extruding shapes by default it enables real-world mapping so you dont need to even apply the UVW modifier. Same goes when creating Boxes/Spheres etc.
https://ibb.co/G76GWR2
I get this result by selecting the horizontal faces and apply another UVW map then rotate, is there a better way ?
If its one piece of geometry then rotating it that way is probably quick enough. If you are making these components separately with boxes/shapes when building the cabinets etc then it does depend on the viewport you create it. For example this is when I create a box in top view, all edges are aligned automatically the correct direction.
This is creating the object in front view, now I have to select the edge faces to rotate them. This technique applies to many things in 3dsmax like when doing sweeps/lofts etc.
I don't understand corona Triplanar map, how can I use it to my advantage in simple interior scenes ?
romullus could probably answer this one better since I don't really use it much these days however as far as I'm aware you can also do mapping with it by rotating the axis within the material instead of doing it for each face like you requested (without needing multiple uvw maps). It also has other features like blending to removing visual tiling etc. You can watch a few videos about it Corona has online for different use cases as well.
Example of using the Corona Triplanar with only 1 uvw map. Default settings
Then if you enable disable "use map X for all axes" and rotate the W:90 in the Z axes you have the expected behavior (or use the Rotate settings in the bottom Rollout and keep use map for X for all axes enabled for a faster workflow)
The main benefit really by using the Realworld mapping option means that in the long run once you save all your materials to a library you are basically just creating shapes/extruding, slapping on the materials and you always know it will be the correct scale and/or direction so you dont need modifiers, dont need to double check scale etc.
If you really want to get technical later on you can do as I said earlier about the tile reference - meaning when you author textures you can create them at the correct scale before going in 3D so making sure all the wood grain is correct for that texture resolution etc, making sure your tiles are exactly 60x60cm etc. Then when you apply these in 3D using your saved library as a base for your new material you already know those tiles/wood grain will be the correct scale. You can really move at a fast pace if doing lots of Set work.